Thread: LIMP mode?

Originally Posted by GEK064

Hi All,

Well I finally got my 99D2 duel fuel back after major surgery (rebuilt motor after slipped liner etc) and the mechanic tells me that the gas system is wired incorrectly causing it to run in limp mode. Apparently the fault causes the ECU to shut the injectors or similar……What does that mean? What does it mean to run in limp mode? I had gas system replaced about two ago and yes she run albeit not perfectly but always expected it to be less than perfect due the to gas. (Yes I planning an injected system but need to pay off the rebuild first).

So my question again what is limp mode?
Is it bad to run in limp mode until I find out how to sort it out?
How do you sort it out?

In the mean while, Yes the 4.6l just rocks my world.

Almost certainly it means whoever cut the power to the injectors also cut the wire to the ECU that tells it there is power at the injectors. If it runs OK on both fuels it won't do any harm. However armed with a wiring diagram your sparky should be able to trace the brown/orange stripe wire to the ECU and see if it remains powered with the gas on. If not a simple bridging wire will do it.

Thanks for that...thinking about it would it not make sense to disconnect the injectors since the gas is not going through them? Apparently once I swtich on the gas the petrol side will also go into limp mode.....if not going through the injectors how would the petrol get into motor....in limp mode for petrol?

Originally Posted by GEK064

Thanks for that...thinking about it would it not make sense to disconnect the injectors since the gas is not going through them? Apparently once I swtich on the gas the petrol side will also go into limp mode.....if not going through the injectors how would the petrol get into motor....in limp mode for petrol?

To run on gas, the gas system has to turn off the injectors, otherwise how would you stop petrol running at the same time? It's the petrol ECU that goes into "limp home" mode, not the injectors. All because someone cut the wrong wire. All it means for you is that the petrol ECU isn't able to control the petrol as well when in "limp home" mode, so it may run a little rough. Usually all you need to do if you want to run petrol is to turn off the engine, and restart with the selector switch on to petrol. That clears the fault until you run on gas again.